An ambitious £30 billion plan for a high-speed rail (HSR) network was proposed today by the Government.

But the first stage of the project, a London to Birmingham HSR line, will not be completed before 2026 - at the earliest.

Also, the HSR plans will need substantial public funding and an intense period of consultation, particularly as 440 homes on the route are under threat of demolition.

There are also concerns the London-Birmingham route plans do not, as yet, include direct links to High Speed One (the Channel Tunnel rail link) or to Heathrow airport.

The Government will also have to withstand the political and environmental concerns engendered by the fact that the route passes through Tory heartlands in the Chiltern Hills in Buckinghamshire.

The plans, announced today by Transport Secretary Lord Adonis, were based on a report on HSR by Whitehall-commissioned body HS2.

Running from Euston in London, the first part of the route - from London to Birmingham - would start in 2017, cost between £15.8 billion and £17.4 billion and reduce the journey time between the UK's two biggest cities to between 30 and 50 minutes.

This line could be completed by 2026 and after that there would be two additional forks either side of the Pennines forming a Y-shaped route.

The west-sided fork would go to Manchester, with the east-side one passing through the East Midlands to Sheffield and Leeds.

Both of the forks would then link with existing lines to Newcastle, Glasgow and Edinburgh.

Journey times between London and Manchester, Leeds and Sheffield would come down from around two hours 10 minutes now to 75 minutes when the new network is in place. London to Glasgow and Edinburgh journey times would be reduced to just three and a half hours.

The Birmingham city centre station for the HSR network would be at Curzon Street and there would be an interchange station with the cross-London Crossrail project west of Paddington at Old Oak Common in west London as well as an interchange station near to Birmingham airport.

Journey times between Old Oak Common and Birmingham airport would be as quick as 31 minutes.

Lord Adonis said the Crossrail Interchange station near Paddington would provide an 11-minute express service to Heathrow.

But he did not entirely rule out the west London airport having its own HSR station, announcing that former Tory transport secretary Lord Mawhinney had been asked to advise on the best way forward for Heathrow.

Lord Adonis said the HSR network would create an estimated 10,000 jobs. The cost per mile of HSR beyond Birmingham would be around half that of the cost per mile of the route from London to the West Midlands city.

The overall cost of about £30 billion would be phased over more than a decade after the start of construction which would not be until after the completion of Crossrail in 2017.

Of the homes threatened with demolition, 247 (or 56% of the total) would be in the Euston area.

Lord Adonis said there would be an exceptional hardship scheme for those whose properties might be directly affected by the line.

He added that no firm decision on the project would be made until there had been "very intensive consultation".

Explaining that HSR was "very dear to his heart", Lord Adonis said such a project was preferable to the "patch and mend jobs" done in the past.

Prime Minister Gordon Brown hailed the announcement as "most exciting" but the Conservatives said Labour had betrayed the Tories' own HSR plans which envisage direct link to Heathrow and which could be started in 2015 - two years ahead of the Government's plan.

Lord Adonis's announcement was generally well received, although the Institute of Directors summed up widespread concerns when it said: "The sums earmarked for HSR are huge and we would be concerned if they came at the expense of crucial investment in the road network, a third runway at Heathrow and the existing rail network."

Rail customer watchdog Passenger Focus said passengers would welcome "this bold plan", while the Association of Train Operating Companies said the announcement "confirms rail as integral to the future success of the British economy".

The CBI warned that private sector support for the concept of HSR "should not be misread as a willingness to write a blank cheque", while airline pilots' union Balpa said it would be "crazy" not to have a direct link to Heathrow.